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Organizing Engineering

Research Papers (46)

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(:)

Setting of research ():??

Research problem () :?

Quantitative specification of problem () :

Importance of problem () :,?

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(:)

Research objective ()

Methodology to achieve objective()

Anticipated results ()

Contribution to field ()

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( :) The fluid jet polishing (FJP) method originated from

the demand for miniaturized optical elements in recent years and

the inability of the conventional polishing method can not satisfy

the fabrication requirements of those elements. The FJP method

facilitates the removal of nanometer deep material, subsequentlycorrecting errors in the optical elements.

However, the FJP method fails to comply with the

requirement of a higher pressure, i.e. >6 bar, to pump the slurry

in order to remove the material of elements. Additionally, theshape that the FJP produces on the surface is not the Gaussian

distribution, thus making it extremely difficult to more accurately

control form correction.

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( :) For instance, the FJP method hasdifficult in satisfying the requirement of form error

/10 for small optical elements.

The inability to optimize thedesign of an optical system owing to limitations ofthe FJP method makes it impossible to achievehigh precision in product manufacturing.

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(:) Based on the above, we should develop amodified FJP method to ensure not only that the shape isclose to Gaussian distribution with a low pressure air source,but also that the resolution of material removal should besmall and stable.

To do so, slurry can be carried with low airpressure, based on use of siphonic and laminar flow theories.The Gaussian shape can then be achieved by using a nozzledifferent from the conventional one, in which both air andslurry can pass through simultaneously. Next, fine resolutionof material removal can be obtained by optimization of theslurry concentration and air pressure.

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(:) As anticipated, the modified FJPmethod can produce stable material removal lessthen 50 nm deep by using 1~2 bar air pressuresource and the new nozzle. Via the modified FJP

method, small optical elements can be fabricatedusing accurate material removal.

Moreover, the enhanced capability ofmaterial removal can fabricate precise optical

elements, ultimately improving the performance ofan optical system.

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( :) Extensively adopted in the opto-electronics industry

for producing polymer optical elements such as condenser lens,

light pipe, lens array, and Fresnel lens for mobile devices,

injection molding technology varies the temperature and

pressure in a polymer-based mold to reduce the number ofshrinkage defects in products.

The conventional means of optimizing process

parameters is inaccurate owing to its reliance on the subjective

experience of an operator to eliminate shrinkage defects in

products. Shrinkage can vary based on the polymer material,

geometrical configuration of the part, subsequently explaining

the complexity of the shrinkage phenomenon and the difficulty in

eliminating shrinkage faults.

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( :) For instance, the conventional approach fails toreduce shrinkage defects in products to less than 2%. Injection moldingis an extensively adopted polymer process in which molten polymerflows into a closed chamber for solidification. The final dimensions andgeometrical configuration of the product is of priority concern in termsof manufacturing quality. Shrinkage refers to the deviation between the

dimension of the cavity and final part. Therefore, as minimization of theshrinkage is anticipated, an operator can increase the holding pressureand mold temperature to eliminate shrinkage faults during the injectionmolding process. However the operator can not determine theappropriate values of process parameters immediately.

Moreover, in addition to lacking a pre-compensated

mold cavity, the conventional injection molding process alsomanufactures the mold first, making a high yield rate for productsimpossible and ultimately increasing fabrication costs. The inability toreduce shrinkage defects in products to less than 2% makes itimpossible to comply with assembly specifications and increasesoverhead manufacturing costs.

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(:) Based on the above, we should develop an injectionmolding method that can accurately estimate shrinkage defectsduring product manufacturing by estimating the shrinkage rate ofa product part and pre-compensation of the mold cavity viasimulation, ultimately reducing shrinkage defects in products and

streamlining the manufacturing process. To do so, shrinkage of wafer products can bereduced based on mold shrinkage compensation. The shrinkagecompensation rates for various materials can then bedetermined via computer-aided engineering (CAE) simulation.Next, compensation dimensions of shrinkage and injection

molding process parameters can be optimized by performingCAE simulations repeatedly. Additionally, design can besimplified and manufacturing time significantly lowered by usingthose compensation rates, which are stored in a database madeavailable for engineers.

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(:) As anticipated, the proposed injectionmolding method can streamline product design bydecreasing the shrinkage rate of defectiveproducts to less than 2%.

Importantly, the proposed method canensure pre-compensation of the mold part,ultimately ensuring high precision in themanufacturing of exterior injection mold parts.

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